This invention relates to preparing preforms.
Preforms are thermoset preparations used in thermoset molding processes. They consist of a thermoset resin which is not fully cured, and often contain fillers, reinforcements, and additives. Preforms are usually prepared in the form of pills, biscuits, or tablets. Preforms are typically prepared from preprocessed thermoset resins, which are produced by mixing a granular thermoset resin with the desired reinforcements, fillers, and additives in a preprocessing extruder. The preprocessed resin is extruded from the preprocessing extruder as a thick, shapeless paste, which is then cooled and formed into a sheet. The sheet is ground into a fine powder, which is then compacted under pressure to form the preforms.